RADIATIVE NEUTRON-PROTON CAPTURE IN EFFECTIVE CHIRAL LAGRANGIANS

We calculate the cross section for the thermal n+pd+ process in chiral perturbation theory to next-to-next-to-leading order using heavy-fermion formalism. The exchange current correction is found to be (4.50.3)% in amplitude, and the chiral perturbation at one-loop order gives the cross section th=3342 mb, which is in agreement with the experimental value 334.20.5 mb. Together with the axial-charge transitions, this provides a strong support for the power of chiral Lagrangians for nuclear physics. © 1995 The American Physical Society.